1. Field of the Invention
The present invention relates to a sheet processing apparatus and an image forming system.
2. Description of Related Art
Conventionally, there is known an edge misalignment of a saddle-stitched booklet between a front surface and a back surface due to the folding line shifting from a central position when the saddle-stitched booklet is laid on its side for edge trimming.
In order to resolve such edge misalignment, there is suggested a method of trimming by holding the saddle-stitched booklet in a vertical state with the folding lineup in Japanese Patent Application Laid Open Publication No. 2013-35668, for example.
In such method, the edges of the saddle-stitched booklet enter a trimming section while the saddle-stitched booklet in the vertical state being held around the folding line by a holding section, and thus, the saddle-stitched booklet needs to be conveyed to the holding section in the vertical state after the half folding and saddle stitching processing.
For example, Japanese Patent Application Laid Open Publication No. 2013-107747 describes a technique for conveying the saddle-stitched booklet by using an XY table while placing the saddle-stitched booklet on a saddle-shaped placement section which supports the inferior angle portion at the folded part of the booklet from below. In Japanese Patent Application Laid Open Publication No. 2013-107747, a conveyance speed is controlled according to conditions of the saddle-stitched booklet in order to prevent the shifting of the saddle-stitched booklet during conveyance.
However, in Japanese Patent Application Laid Open Publication No. 2013-107747, since the saddle-stitched booklet is merely placed on the saddle-shaped placement section, the conveyance speed needs to be extremely low in order to prevent the saddle-stitched booklet from falling down and the folding line from shifting due to the conveyance operation, and thus, productivity is reduced.